The invention relates to a non-rigid marine platform with surface hydrocarbon production wellheads for deep water applications, the platform comprising flexible piles anchored to the seabed and supporting a deck equipped with production means (including the wellheads) connected to the upper end of conducting tubes guided by guide frames spaced along the flexible plies.
Exploitation of hydrocarbons in the deep ocean is today envisaged according to two different arrangements. Either one or more structures of the fixed or compliant type and supporting all the production equipment are mounted on the seabottom, or subsea wellheads are installed in the seabottom and the rest of the production equipment is provided on a floating support consisting of a converted ship or a platform of the semi-submersible type, the wellheads being connected to the floating support by means of flexible riser pipes.
The first type of system has the advantage of using very well known, well tested and highly reliable oil equipment, largely proven in land-based oil developments and in most marine developments, but has the disadvantage of being rather heavy and necessitating an expensive infrastructure. For this reason, this type of arrangement is well suited for the development of large hydrocarbon deposits for which heavy investment is envisaged.
The second type of system has the advantage of using equipment which can be salvaged at the depletion of the hydrocarbon field and may very easily be moved to other production sites. This type of development is thus very suitable for bringing into production marginal fields for which investment must be low, the duration of production generally being quite short.
However, this type of system has the disadvantage of requiring the use of subsea wellheads, which are more expensive than conventional wellheads, and in particular much more difficult to install, operate and maintain.
Furthermore, the connection by flexible risers between the floating support and the seabottom is always delicate and requires a relatively high degree of maintenance.